How to Switch LLM Providers Without Breaking Your Product

A step-by-step playbook for migrating from one LLM provider to another with zero downtime and validated output quality.

Assess your current integration depth

Catalog every place your codebase calls the LLM API: endpoints, prompt templates, response parsers, error handlers, and billing logic. The more tightly coupled you are to a single provider's SDK and response format, the more work the migration will require. This audit also reveals undocumented dependencies like provider-specific token counting.

Evaluate alternative providers and models

Run your top 50 production prompts through candidate models and compare output quality, latency, and cost. LLMWise Compare mode automates this: send one request and get structured results from every model, making provider evaluation a single afternoon instead of a multi-week project.

Build or adopt an abstraction layer

Decouple your application from any single provider by routing all LLM calls through a unified interface. This can be a thin wrapper you build or a platform like LLMWise that provides an OpenAI-compatible API for nine models across five providers. An abstraction layer makes future switches trivial.

Migrate traffic incrementally

Start by routing 5-10 percent of traffic to the new model while monitoring error rates, latency, and user feedback. Increase the percentage gradually. If metrics degrade, roll back instantly. LLMWise lets you adjust model routing per request, so you can run canary deployments without infrastructure changes.

Validate with replay before full cutover

Before sending 100 percent of traffic to the new model, replay your last 30 days of production requests through it and compare outputs to the original model. LLMWise Replay Lab does this automatically, showing you quality and cost differences across your real-world prompt distribution so you can cut over with confidence.

Key takeaways

✓An abstraction layer is the best long-term investment: it turns a multi-week migration into a config change.

✓LLMWise Replay Lab lets you validate a provider switch against real production traffic before committing.

✓Incremental traffic migration with instant rollback eliminates the risk of a big-bang cutover.

Common questions

How long does it take to switch LLM providers?

If you are tightly coupled to one provider's SDK, a full migration can take two to six weeks. With an abstraction layer like LLMWise already in place, switching is a configuration change that takes minutes because the API contract stays the same.

Will my prompts work the same on a different model?

Not always. Each model has its own strengths, system-prompt behavior, and token limits. That is why replay testing is critical: it shows you exactly which prompts produce different outputs so you can adjust them before switching.

Try it yourself

500 free credits. One API key. Nine models. No credit card required.

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